Lordosis Support

ABSTRACT

The invention relates to a lumbar support for a seat backrest, having a lumbar support basket  12  arranged in a frame  10  of a seat backrest, a pulling device which changes the position of the lumbar support basket  12  relative to the frame, characterised in that the pulling device has two pull cables  16, 17  which are coupled to the lumbar support basket  12  and the frame in such a way that when tension is exerted on the pulling device the lumbar support basket  12  is moved relative to the plane defined by the frame  10  of the seat backrest.

The present invention relates to a lumbar support for a seat backrest.The invention relates in particular to a lumbar support fitted inbackrests of motor vehicle seats, office furniture seats, or domesticfurniture seats.

Lumbar supports are fitted in seat backrests in order to providesufficient support in the lumbar-vertebra or lordosis region of a personseating on the seat by forming a corresponding supporting surface. Forthis, the lumbar support customarily has a lumbar support basket whichis fastened to a frame arranged in the seat backrest. Furthermore, apulling device by which the position of the lumbar support basket can bechanged relative to the frame is customarily provided.

In the prior art, a lumbar support basket is known which is fastened onone side to the support frame, while the other side is fastened via aBowden cable to the other frame side, the position of the support basketrelative to the plane defined by the frame being changed when tension isexerted on the Bowden cable. The unilateral tensile load results in anasymmetrical action of the tensile load, so that the lumbar supportbasket is also moved laterally when tension is exerted on the Bowdencable, and not just perpendicularly to the plane defined by the frame.Furthermore, the movement does not take place symmetrically to the axiswhich is perpendicular to the plane defined by the frame, so that theperson sitting on the seat feels unsymmetrical relief of the strain onthe lordosis region when tension is exerted on the Bowden cable.Furthermore, a relatively long pull length is necessary for a relativelysmall movement of the lumbar support basket.

An object of the present invention is to provide a lumbar support whichenables a symmetrical movement of the lumbar support basket whileachieving a greatest possible adjustment of the lumbar support basketfor a small pulling movement.

This object is achieved according to the invention by the independentclaim. Preferred embodiments of the invention are described in thedependent claims.

According to the invention, the lumbar support for a seat backrest has alumbar support basket arranged in a frame of a seat backrest.Furthermore, a pulling device which changes the position of the lumbarsupport basket relative to the frame is provided. The pulling device hastwo pull cables which are coupled to the lumbar support basket and theframe in such a way that when tension is exerted on the pulling devicethe lumbar support basket is moved relative to the plane defined by theframe of the seat backrest. Symmetrical tension on the lumbar supportbasket is achieved by means of the two pull cables of the pullingdevice, so that a symmetrical movement of the lumbar support basket withrespect to an axis which is perpendicular to the plane defined by theframe of the seat backrest is achieved. At the same time, by means ofthe two pull cables, for the same pull length twice the adjusting travelis achieved compared with the prior art, in which the lumbar supportbasket is equipped with only one pull cable.

Preferably, the lumbar support basket has a guiding device in which thepulling device is movably guided. According to a preferred embodiment,the two pull cables are movably located in the guiding device.Preferably, the pulling device is a Bowden cable, the actuator foractuating the Bowden cable being attached to the frame.

According to a further preferred embodiment, both pull cables arefastened at their one end to the frame. In this embodiment, therespective other ends of the pull cables are fastened to the actuator.The pull cables can, in one embodiment, run together from the actuatorup to the guiding device, the pull cables branching at the guidingdevice and each pull cable running from the branching up to the frame,where it is fastened.

Furthermore, preferably the pull cables run upon the branching at theguiding device in opposite directions and are fastened to opposite sidesof the frame. These two lateral parts of the pull cables from thebranching up to the frame are responsible for the position of the lumbarsupport basket relative to the frame.

When tension is exerted on the pull cables, the region of the pullcables from the fastening to the frame up to the guiding device can beshortened, whereby the lumbar support basket is displaced relative tothe plane defined by the frame. In this case, the region in which thetwo pull cables run jointly up to the guiding device lengthens. Theregion of one pull cable from the guiding device to the lateral frame isshortened, this region likewise for the other pull cable from theguiding device to the other frame side likewise being shortened, wherebythe adjusting travel of the lumbar support basket is doubled for a givenpull length.

According to another embodiment, the two pull cables are arranged insuch a way that the second pull cable runs from the actuator up to theguiding device. The first pull cable runs from one frame side via theguiding device to the other frame side and is coupled to the second pullcable in such a way that when tension is exerted on the second pullcable the effective cable length of the first pull cable between the twoframe sides is shortened. In this case, when tension is exerted on thesecond pull cable a subregion of the first pull cable is moved in thedirection of the second pull cable perpendicularly to the course of thefirst pull cable, so that the effective cable length of the first pullcable from the first frame side to the second frame side shortens.

The invention is explained in more detail below using an exemplaryembodiment with reference to the accompanying schematic drawings, inwhich:

FIG. 1 shows a front view of the lumbar support arranged in the frame ofa seat backrest,

FIG. 2 shows a rear view of the lumbar support in the frame,

FIG. 3 shows a plan view of the lumbar support in an unloaded position,

FIG. 4 shows a plan view of the lumbar support in a loaded position,

FIG. 5 shows an enlarged view of the lumbar support in a front view,

FIG. 6 shows an enlarged rear view of the lumbar support,

FIG. 7 shows a detail view of the guiding device in the unloadedposition of the Bowden cable, and

FIG. 8 shows a detail view of the guiding device in the loaded positionof the Bowden cable.

FIG. 1 shows a front view of a frame 10 which is part of a seat backrest(not illustrated) of a motor vehicle seat. Furthermore, in the lowerregion of the seat frame a lumbar support 11 having a lumbar supportbasket 12 is provided. The lumbar support basket is actuated via aBowden cable, an actuator 13 fastened to one side of the frame 10 beingprovided in order to actuate the Bowden cable. In the embodimentillustrated in FIG. 1, two different positions of the actuator 13 areillustrated, the actuator 13 a and the actuator 13 b. The two actuators13 a and 13 b show only different possible arrangements of a singleactuator in the backrest frame, there being no provision for twoactuators. Provided above the lumbar support basket 12 is a wire mat 14which can be connected to the frame 10, for example, via springs (notillustrated). The wire mat 14 can also be connected to the lumbarsupport basket 12. A connection between lumbar support basket 12 andwire mat 14 is not absolutely necessary, however.

As can also be seen in FIG. 2 inter alia, two pull cables 16 and 17 ofthe Bowden cable are guided in a cable sleeve 15. Starting from theactuator 13, these two pull cables run jointly in the cable sleeve 15 upto a guiding device 18, at which they branch, one pull cable 16 beingfastened to one side 10 a of the frame 10, and the pull cable 17branching off at the guiding device, running to the other side of theframe 10 and being fastened there. As can be seen in FIGS. 5 and 6 interalia, the lumbar support basket is designed in the form of a plate andis slightly concavely curved in order to guide the lower lumbar region.The lumbar support basket has a middle section 20, to which the guidingdevice 18 is attached. Furthermore, two lateral sections 21 and 22 areprovided. Braces 23 are provided on the side of the lumbar supportbasket facing away from the back of the person leaning against the seatbackrest.

As can be seen in FIGS. 2 and 6, the cable sleeve 15 is attached to theguiding device 18. The guiding device 18 has two arcuate guidingsections 24 and 25 which effect the diversion of the two pull cables 16and 17. The two pull cables 16 and 17 are movably arranged in theguiding device and are diverted by about 90° substantially in oppositedirections at the diversions 24 and 25 and guided in guiding eyes 26 onthe lumbar support basket before being fastened to the frame 10 byfixing elements 27.

In FIGS. 3 and 4, the different positions of the lumbar support basketrelative to the frame are depicted. In the position illustrated in FIG.3, no tension is exerted on the pull cables 16 and 17 and the lumbarsupport basket is in a rest position where it is pushed by upholstery(not illustrated) of the seat into the position illustrated in FIG. 3.In this position of FIG. 3, the two cables run together, as illustratedin FIG. 7, up to a joining nipple 28 which joins the two pull cables 16and 17, before they are guided by the diversions to the sides of theframe. If the actuator 13 is now actuated, tension is exerted on the twopull cables 16 and 17, which moves the joining nipple and the jointlyrunning region of the pull cables, as illustrated in FIG. 8, in thedirection of the cable sleeve 15. As a result, the region of the pullcables 16 and 17 which previously ran horizontally, diverted by thediversions 24 and 25, is in each case shortened by the height h.Overall, the region of the pull cables which runs horizontally betweenthe two sides 10 a and 10 b of the frame 10 is shortened by the height 2h. Overall, the effective horizontal pull cable length thus shortens bythe height 2 h. This horizontal pull cable length is responsible for theposition of the lumbar support basket 12 relative to the plane definedby the frame. As a result, the lumbar support basket is, as illustratedin FIG. 4, pushed in the direction of the back (not illustrated).

From the foregoing description, the following advantage is thus obtainedfor a person skilled in the art by means of the invention.

Firstly, the lumbar support basket is moved symmetricallyperpendicularly to the plane defined by the frame. Furthermore, anadjustment of the lumbar support basket by the length 2 h is achieved bya pull length h at the actuator. The actuator for actuating the pullcable can be actuated either manually or by an electric motor.

Instead of the two pull cables 16 and 17 illustrated in the figures, itis also possible to provide a first pull cable running from one side 10a of the frame to the other side 10 b, while providing a second pullcable running from the actuator up to the joining nipple 28. The firstpull cable is in this case joined to the second pull cable at thejoining nipple 28. When tension is exerted on the second pull cable,which is fastened to the actuator, this pull cable lifts the other pullcable in the direction of the cable sleeve 15, so that once again thelumbar support basket is moved into the position illustrated in FIG. 4,since the length of the pull cable stretching between the two sides ofthe frame is shortened by the length 2 h.

LIST OF REFERENCE SYMBOLS

-   10 Frame-   10 a Side-   10 b Side-   11 Lumbar support-   12 Lumbar support basket-   13 Actuator-   14 Wire mat-   15 Cable sleeve-   16, 17 Pull cables-   18 Guiding device-   20 Middle section-   21, 22 Lateral sections-   23 Brace-   24, 25 Diversion-   26 Guiding eyes-   27 Fixing elements-   28 Joining nipple

1-8. (canceled)
 9. Lumbar support for a seat backrest, having a lumbarsupport basket arranged in a frame of a seat backrest, a pulling devicewith a Bowden cable, the actuator of the Bowden cable being attached tothe frame, wherein the pulling device changes the position of the lumbarsupport basket relative to the frame and has two pull cables which arecoupled to the lumbar support basket and the frame in such a way thatwhen tension is exerted on the pulling device the lumbar support basketis moved relative to the plane defined by the frame of the seatbackrest, wherein the first pull cable runs from one frame side to theother frame side, and the second pull cable runs from the actuator up toa guiding device attached to the lumbar support basket, in which thepull cables are movably guided, the two pull cables being coupled toeach other at the guiding device in such a way that when tension isexerted on the second pull cable the cable length of the first pullcable between the two frame sides is effectively shortened.
 10. Lumbarsupport for a seat backrest, having a lumbar support basket arranged ina frame of a seat backrest, a pulling device which changes the positionof the lumbar support basket relative to the frame and which has twopull cables which are coupled to the lumbar support basket and the framein such a way that when tension is exerted on the pulling device thelumbar support basket is moved relative to the plane defined by theframe of the seat backrest, wherein the pulling device is a Bowdencable, the actuator of the Bowden cable being attached to the frame,wherein the pull cables are running from the actuator together up to aguiding device attached to the lumbar support basket in which the pullcables are movably guided, and are branching at the guiding device, eachpull cable running from the branching up to the frame, to which it isfastened.
 11. Lumbar support according to claim 10, wherein both pullcables are fastened by one of their ends to the frame.
 12. Lumbarsupport according to claim 10, the pull cables upon the branching beingdiverted in opposite directions and fastened to opposite sides of theframe.
 13. Lumbar support according to claim 10, wherein when tension isexerted on the pulling device the regions of the pull cable from thefastening to the frame up to the guiding device are shortened, wherebythe lumbar support basket is displaced relative to the plane defined bythe frame.